In a world with an intellectual history of seven thousand years behind it, where do Pakistanis stand, what are they doing, what do they aspire to be, and what ought they to be doing? This Blog takes Notes of all of that ...

Friday, October 11, 2013

In violent Pakistan, violent birth of an island

A
small island that appeared in the Arabian Sea off Pakistan after an
earthquake last week most likely formed when the shaking released methane gas
and water trapped in undersea sediments. The gas and water forced part of the
seabed to the surface, experts said.

[The New York Times]

“It
looked as if a section of shallow seafloor had simply been pushed up,” said
Game McGinsey, a volcanologist with the United States Geological Survey.
Photographs of the island, which measures roughly 100 feet by 250 feet and
rises about 60 feet above the water, showed a rough-textured surface suggesting
that the seafloor had risen and cracked, he said.

Dr.
McGinsey said the way the island was created was similar in some ways to that
of a so-called mud volcano, in which gas and water force mud up through vents
to the surface. In those cases, the flow of mud normally continues for some
time, similar to the way lava flows from a conventional volcano.

There
are some long-lived mud volcanoes in the region, Dr. McGinsey said, but this
one appeared to be a one-time event, with no sign of continuous flow. “It’s not
a mud volcano in the classic sense,” he said.

The
magnitude 7.7 quake struck Tuesday, killing more than 500 people and flattening
homes in the southwestern province of Baluchistan. It was followed by a
6.8-magnitude aftershock on Saturday that killed at least 15 more people.

The
initial quake was centered about 40 miles north of the city of Awaran and about
250 miles from the port town of Gwadar, where the new island appeared in
shallow waters about a half-hour later. Townspeople and scientists who visited
the island told news agencies that it was muddy and rocky and was emitting
flammable gas. Methane, the main component of natural gas, is highly flammable.

The
quake occurred in the Makran subduction zone, a vast and complex tectonic
feature stretching from Pakistan to Iran where three plates, the Indian,
Arabian and Eurasian, meet. As the Arabian plate slides under the Eurasian,
sediments containing water and methane are compressed, said Michael Steckler, a
geophysicist with the Lamont-Doherty Earth Observatory, a part of Columbia
University.

“In subduction zones you get a lot of
overpressure,” Dr. Steckler said. Even a relatively far-off earthquake can
produce enough shaking to fracture the sediments and release the gas and water,
he said.

The
methane is created through the action of bacteria on organic matter, and would
have been trapped in the sediments as free molecules of gas. The Arabian Sea is
also home to large quantities of methane hydrates, icy cagelike structures of
water molecules with methane molecules inside, and immediately after the island
formed there was speculation that hydrates, not free methane, had been
released.

But
hydrates form only under high pressure and low temperatures, and Carolyn
Ruppel, director of the survey’s hydrate research program, said water in the
area was too shallow, and temperatures in sediments far too high, for hydrates
to exist.

Similar
islands formed in the Arabian Sea after an 8.1-magnitude earthquake in 1945. (A
recent study by scientists in Germany showed that that quake set off the
release of free methane from sediments, releases that continue today.) Islands
also formed after quakes in 1999 and 2010.

Such
islands eventually disappear, eroded by the action of tides and waves. Dr.
Steckler said that the one that formed in 1999, for instance, was gone in a few
months, a victim of monsoon surges.

“This one’s coming up after the monsoon,”
he said, “so we’ll see how long it lasts.”

[A version of this article appeared in print on October 1, 2013, on page D3 of the New York edition with the headline: A Quake Shakes Loose an Island.]

The Blogger

The blogger cherishes a cosmopolitan spirit; he is a moralist; a rationalist; a philosopher; a political philosopher; he believes in Classical Liberalism, as a Theory of Conduct.
He has substantially contributed to the founding of the first free market think tank of Pakistan, Alternate Solutions Institute.
He is a writer who wrote / published dozens of articles on a variety of issues, and is author of 4 books.
He wrote / published short-stories in Punjabi, a regional language of Pakistan.
He composes poetry both in Urdu and Punjabi, and has already published one collection.